by Cixin Liu
“I wasn’t. I’ve said again and again that I’m an ordinary guy. My identity is nothing more than what you’ve already looked up.”
The Senior Official nodded. It was impossible to tell whether Bai Bing’s words had reassured him, or added to his concern.
“Sit, let’s all sit.” The Senior Official waved a hand at Lu and Chen, both still standing, and drew closer to Bai Bing. “Young man,” he said solemnly. “Let’s get to the bottom of all this today, okay?”
Bai Bing nodded. “That’s my plan too. I’ll start from the beginning.”
“No, that won’t be necessary. We heard everything you said to Song Cheng earlier. Just continue where you left off.”
Bai Bing was momentarily at a loss for words, unable to remember where he’d stopped.
“Atomic-level model of the entire universe,” the Senior Official reminded him, but seeing that Bai Bing still couldn’t figure out how to start talking again, he added his own input. “Young man, I don’t think your idea is feasible. Superstring computers have ultimate capacity, yes, providing the hardware basis for running this sort of simulation. But have you considered the problem of the initial state? To make a digital mirror of the universe, you must start the simulation from some initial state—in other words, to construct a model that represents the universe on an atomic level, for the instant the model starts at, you’ll have to input the status at that instant of every atom in the universe into the computer, one by one. Is this possible? It wouldn’t be possible with the egg you mentioned, let alone the universe. The number of atoms in that egg outnumber the number of eggs ever laid since the beginning of time by orders of magnitude. It wouldn’t even be possible with a bacterium, which still contains an astonishing number of atoms. Taking a step back, even if we put forth the near unimaginable manpower and computing power needed to find the initial state of a small object like the bacterium or the egg on an atomic level, what about the boundary conditions for when the model runs? For example, the outside temperature, humidity, and so on needed for a chicken egg to hatch. Taken on the atomic level, these boundary conditions will require unimaginable quantities of data too, perhaps even more than the modeled object itself.”
“You’ve laid out the technical problems beautifully. I admire that,” Bai Bing said sincerely.
“The Senior Official was once a star student in the field of high-energy physics. After Deng Xiaoping’s reforms restored university degrees, his was one of the first classes to receive master’s degrees in physics in China,” said Lu Wenming.
Bai Bing nodded in Lu Wenming’s direction, then turned toward the Senior Official. “But you forget, there’s a moment in time in which the universe was extremely simple, even simpler than eggs and bacteria, simpler than anything in existence today. The number of atoms in it at the time was zero, see. It had no size and no composition.”
“The big bang singularity?” the Senior Official said immediately, almost no delay between Bai Bing’s words and his. It was a glimpse at the quick, agile mind beneath his slow and steady exterior.
“Yes, the big bang singularity. Superstring theory has already established a perfect model of the singularity. We just need to represent the model digitally and run it on the computer.”
“That’s right, young man. That really is the case.” The Senior Official stood and walked to Bai Bing’s side to pat his shoulder, revealing rare excitement. Chen Xufeng and Lu Wenming, who hadn’t understood the exchange that had just taken place, looked at them with puzzled expressions.
“Is this the superstring computer you brought out of the research center?” the Senior Official asked, pointing at the briefcase.
“Stole,” said Bai Bing.
“Ha, no matter. The software for the digital mirror of the big bang is on it, I expect?”
“Yes.”
“Run it for us.”
CREATION GAME
Bai Bing nodded, hauled the briefcase onto the desk, and opened it. Beside the display equipment, the briefcase also contained a cylindrical vessel. The superstring computer’s processor was in fact only the size of a pack of cigarettes, but the atomic circuitry required ultralow temperatures to operate, so the processor had to be kept submerged in the insulated vessel of liquid nitrogen. Bai Bing set the LCD screen upright and moved the mouse, and the superstring computer awoke from sleep mode. The screen brightened, like a dozing eye blinking open, displaying a simple interface composed of just a drop-down text box and a header reading:
Please Select Parameters to Initiate bCreation of the Universe
Bai Bing clicked the arrow beside the drop-down text box. Row upon row of data sets, each composed of a sizable number of elements, appeared below. Each row seemed to differ considerably from the others. “The properties of the singularity are determined by eighteen parameters. Technically, there’s an infinite number of possible parameter combinations, but we can determine from superstring theory that the number of parameter combinations that could have resulted in the big bang is finite, although their exact number is still a mystery. Here we have a small selection of them. Let’s select one at random.”
Bai Bing selected a group of parameters, and the screen immediately went white. Two big buttons appeared in striking contrast at the center of the screen.
Initiate Cancel
Bai Bing clicked Initiate. Now only the white background was left. “The white represents nothingness. Space doesn’t exist at this time, and time itself hasn’t begun. There really is nothing.”
A red number “0” appeared in the lower left corner of the screen.
“This number indicates how long the universe has been evolving. The zero appearing means that the singularity has been generated. Its size is undefined, so we can’t see it.”
The red number began to increment rapidly.
“Notice, the big bang has begun.”
A small blue dot appeared in the middle of the screen, quickly growing into a sphere emitting brilliant blue light. The sphere rapidly expanded, filling the entire screen. The software zoomed out, and the sphere once again shrank into a distant dot, but the ballooning universe quickly filled the screen once more. The cycle repeated again and again in rapid frequency, as if marking the beats to some swelling symphony.
“The universe is currently in the inflationary epoch. It’s expanding at a rate far exceeding the speed of light.”
As the sphere slowed in its growth, the field of view began to zoom out less frequently, too. With the decrease in energy density, the sphere turned from blue to yellow, then red, before the color of the universe stabilized at red and began to darken. The field of view no longer zoomed out, and the now-black sphere expanded very slowly now on the screen.
“Okay, it’s ten billion years after the big bang. At this point, this universe is in a stable stage of evolution. Let’s take a closer look.” Bai Bing moved the mouse, and the sphere rushed forward, filling the whole screen with black. “Right, we’re in this universe’s outer space.”
“There’s nothing here?” said Lu Wenming.
“Let’s see.…” As Bai Bing spoke, he right-clicked and pulled up a complicated window. A script began to calculate the total matter present in the universe. “Ha, there are only eleven fundamental particles in this universe.” He pulled up another massive data report and read it carefully. “Ten of the particles are arranged in five mutually orbiting pairs. However, in each pair, the two particles are tens of millions of light-years apart. They take millions of years to move one millimeter with respect to each other. The last particle is free.”
“Eleven fundamental particles? But after all that talk, there’s still nothing here,” said Lu Wenming.
“There’s space, nearly a hundred billion light-years in diameter! And time, ten billion years of it! Time and space are the true measures of existence! This particular universe is actually one of the more successful ones. In a lot of the universes I created before, even the dimensions of space quickly disappeared, leavi
ng only time.”
“Dull,” harrumphed Chen Xufeng, turning away from the screen.
“No, this is very interesting,” said the Senior Official delightedly. “Do it again.”
Bai Bing returned to the starting interface, selected a new set of parameters, and initiated another big bang. The formation process of the new universe looked to be about the same as the earlier one, an expanding and dimming sphere. Fifteen billion years after creation, the sphere became fully black: the evolution of the universe had stabilized. Bai Bing moved the viewpoint into the universe. Even Chen Xufeng, least interested out of all of them, exclaimed. Beneath the vast darkness of space, a silvery surface extended endlessly in all directions. Small, colorful spheres decorated the membrane like multicolored dewdrops tumbling on the broad surface of a mirror.
Bai Bing brought up the analysis window again. He looked at it for a while and said, “We were lucky. This is a universe rich in variety, about forty billion light-years in radius. Half of its volume is liquid, while the other half is empty space. In other words, this universe is a massive ocean, forty billion light-years in depth and radius, with the solid celestial bodies floating on its surface!” Bai Bing pushed the field of view closer to the ocean’s surface, allowing them to see that the silvery ocean surface was gently rippling. A celestial body appeared in their close-up view. “This floating object is … let me see, about the size of Jupiter. Whoa, it’s rotating by itself! The mountain ranges look amazing when they’re coming in and out of—let’s just call this liquid water! See the water being flung up by the mountain ranges, along its orbit. It forms a rainbow arc above the surface!”
“It’s beautiful, indeed, but this universe goes against the basic laws of physics,” the Senior Official said, looking at the screen. “Never mind an ocean forty billion light-years deep, a body of liquid four light-years deep would have collapsed into a black hole due to gravity long ago.”
Bai Bing shook his head. “You’ve forgotten a fundamental point: This isn’t our universe. This universe has its own set of laws of physics, completely different from ours. In this universe, the gravitational constant, Planck’s constant, the speed of light, and other basic physical constants are all different. In this universe, one plus one might not even equal two.”
Encouraged by the Senior Official, Bai Bing continued the demonstration, creating a third universe. When they entered for a closer look, a chaotic jumble of colors and shapes appeared on the screen. Bai Bing immediately exited. “This is a six-dimensional universe, so we have no way of observing it. In fact, this is the most common case, and we were lucky to get two three-dimensional universes on our first two tries. Once the universe cools down from its high-energy state, the odds of having three available dimensions on the macroscopic scale is only three out of eleven.”
A fourth universe manifested. To the bafflement of everyone: the universe appeared as an endless black plane, with countless bright, silvery lines intersecting it perpendicularly. After reading the analysis profile, Bai Bing said, “This universe is the opposite of the previous one—it has fewer dimensions than our own. This is a two-and-a-half-dimensional universe.”
“Two and a half dimensions?” The Senior Official was astonished.
“See, the black two-dimensional plane with no thickness is this universe’s outer space. Its diameter is around five hundred billion light-years. The bright lines perpendicular to the plane are the stars in space. They’re hundreds of millions of light-years long, but infinitely thin, because they’re one-dimensional. Universes with fractional dimensions are rare. I’m going to make note of the parameters that produced this one.”
“A question,” said the Senior Official. “If you use these parameters to initialize a second big bang, would it produce a universe exactly the same as this one?”
“Yes, and the evolution process would be identical too. Everything was predetermined at the time of the big bang. See, after physics got past the obfuscation of quantum effects, the universe once again displayed an inherently causal and deterministic nature.” Bai Bing looked at the others one by one. He said seriously, “Please keep this point in mind. This will be key to understanding the terrifying things we’ll be seeing later.”
“This really is fascinating.” The Senior Official sighed. “Playing God, aloof and ethereal. It’s been a long time since I’ve felt this way.”
“I felt the same,” Bai Bing said as he stood up from the computer to pace back and forth, “so I played the creation game again and again. By now, I’ve initiated more than a thousand big bangs. The awe-inspiring wonder of those thousand-plus universes is impossible to describe with words. I felt like an addict … I could have kept going like that, never coming into contact with you, never getting involved. Our lives would have continued along our orbits. But … ah, hell … It was a snowy night at the beginning of the year, nearly two in the morning, really quiet. I ran the last big bang of the day. The superstring computer gave birth to the one thousand two hundred and seventh universe—this one.…”
Bai Bing returned to the computer, scrolled to the bottom of the drop-down list, and selected the last set of parameters. He initiated the big bang. The new universe rapidly expanded in a glow of blue light before extinguishing to black. Bai Bing moved the mouse and entered his Universe No. 1207 at nineteen billion years after creation.
This time, the screen displayed a radiant sea of stars.
“1207 has a radius of twenty billion light-years and three dimensions. In this universe, the gravitational constant is 6.67 times 10–11, and the speed of light in a vacuum is three hundred thousand kilometers per second. In this universe, an electron has a charge of 1.602 times 10–19 coulombs. In this universe, Planck’s constant is 6.62…” Bai Bing leaned in toward the Senior Official, watching him with a chilling gaze. “In this universe, one plus one equals two.”
“This is our own universe.” The Senior Official nodded, still steady, but his forehead was now damp.
SEARCHING HISTORY
“Once I found Universe No. 1207, I spent more than a month building a search engine based on shape and pattern recognition. Then I looked through astronomy resources to find diagrams of the geometrical placement of the Milky Way with respect to the nearby Andromeda Galaxy, Large and Small Magellanic Clouds, and so on. Searching for the arrangement within the entire universe gave me more than eighty thousand matches. Next I searched those results for matches for the internal arrangement of the galaxies themselves. It didn’t take long to locate the Milky Way in the universe.” Onscreen, a silver spiral appeared against a backdrop of pitch-black space.
“Locating the sun was even easier. We already know its approximate location in the Milky Way—” Bai Bing used his mouse to click and drag a small rectangle over the tip of one arm of the spiral.
“Using the same pattern-recognition method, it didn’t take long to locate the sun in this area.” A brilliant sphere of light appeared onscreen, surrounded by a large disk of haze.
“Oh, the planets in the solar system haven’t formed yet right now. This disk of interstellar debris is the raw material they’re made up of.” Bai Bing pulled up a slider bar at the bottom of the window. “See, this lets you move through time.” He slowly dragged the slider forward. Two hundred million years passed before them; the disk of dust around the sun disappeared. “Now the nine planets have formed. The video window shows real distances and proportions, unlike your planetarium displays, so finding Earth is going to take more work. I’ll use the coordinates I saved earlier instead.” With that, the nascent planet Earth appeared on the screen as a hazy gray sphere.
Bai Bing scrolled the mouse wheel. “Let’s go down … good. We’re about ten kilometers above the surface now.” The land below was still shrouded in haze, but crisscrossing glowing red lines had appeared in it, a network like the blood vessels in an embryo.
“These are rivers of lava,” Bai Bing said, pointing. He kept scrolling down, past the thick acidic fog. The br
own surface of the ocean appeared, and the point of view plunged lower, into the ocean. In the murky water were a few specks. Most were round, but a few were more complicated in shape, most obviously different from the other suspended particles in that they were moving on their own, not just floating with the current.
“Life, brand new,” Bai Bing said, pointing out the tiny things with the mouse.
He rapidly scrolled the mouse wheel in the other direction, raising their point of view back into space to once again show the young Earth in full. Then he moved the time slider. Countless years flew past; the thick haze covering Earth’s surface disappeared, the ocean began to turn blue, and the land began to turn green. Then the enormous supercontinent Pangaea split and broke apart like ice in spring. “If you want, we can watch the entire evolution of life, all the major extinctions and the explosions of life that followed them. But let’s skip them and save some time. We’re about to see what this all has to do with our lives.”
The fragmented ancient continents continued to drift until, at last, a familiar map of the world appeared. Bai Bing changed the slider-bar settings, advancing in smaller increments through time before coming to a stop. “Right, humans appear here.” He carefully shifted the slider a little further forward. “Now civilization appears.
“You can only see most of distant history on a macro scale. Finding specific events isn’t easy, and finding specific people is even harder. Searching history mainly relies on two parameters: location and time. It’s rare that historical records give them accurately this far back. But let’s try it out. We’re going down now!” Bai Bing double-clicked a location near the Mediterranean Sea as he spoke. The point of view hurtled downward with dizzying speed. At last, a deserted beach appeared. At the far side of the yellow sand was an unbroken grove of olive trees.
